CNC milling service

Our CNC milling service is built around accuracy, repeatability, and expert machining of metal and plastic components.

Penta Precision specialises in high precision CNC milling for complex and critical parts. CNC milling is a subtractive manufacturing process that uses computer-controlled tools to remove material from a solid block. It allows for tight tolerances, repeatable accuracy, and flexibility across materials and part designs. Our CNC milling services are ideal for both prototyping and full production runs, supporting industries across the UK with critical quality demands.

Our CNC milling capabilities

We offer 3-, 4-, and 5-axis CNC milling to accommodate a wide range of geometries and complexities. Our capabilities also include manual milling for simpler parts, as well as prototype and batch production to suit your project’s scale and stage.

Additional services such as design for manufacture (DFM) support, part marking, insert installation, and sub-assembly allow us to support your entire production workflow. A variety of finishing processes are also available to meet specific functional or aesthetic requirements.

We accept 2D files such as PDF and DXF, and work seamlessly with 3D file formats like STEP. From quote to delivery, you receive expert input and clear, responsive communication at every stage.

Lead times

CNC tolerances

Finishing processes

Max dimensions

Tab one

Order Type Quantity Range Typical Lead Time Additional Info
Prototype 1–5 parts 1–4 weeks* May vary based on complexity and material, but is flexible to the part requirements. Contact us early to discuss.
Small Batch Production 6–25 parts 4–6 weeks Can occasionally be reduced to 2–3 weeks depending on capacity and material lead time.
Medium Batch Production 26–100 parts 4–6 weeks Best suited to scheduled or call-off ordering for consistency
High Volume Production 100+ parts 4–6 weeks Longer lead times. Kanban or call-off ordering strongly advised
Kanban / Call-Off Orders Varies 24–48 hours dispatch* Stock held at Penta. Dispatch triggered by usage or schedule. Order is invoiced or paid upon call-off.
Tab two

Process Range of Tolerances Achievable Notes
Milling >±0.01 mm Dependent on part geometry, material and setup. 5-axis offers tighter tolerances and better repeatability.
Turning >±0.005+ mm High-precision turning across billet and bar work, supported by modern multi-axis machines.
Geometric Tolerances >±0.005+ mm* *Depending on material, finishes, and the geometry of the part.
CMM Measurement Verification to ±0.002 mm Achieved using our Axiom Too CMM with 2.3µm volumetric accuracy and temperature compensation.
Tab three

Finishing Process Purpose Additional Information
Hard Anodising Adds a protective oxide layer to aluminium parts. Usually 25–30 microns thick. Typically used for parts designed for the outdoors and general engineering for corrosion resistance. This finish requires hole masking and machining allowance, so use only if needed.
Sulphuric Anodising Adds a decorative layer to aluminium. Less than 5 microns thick. Won’t offer any protection and minimal corrosion resistance. For decorative or aesthetic purposes only.
Bead Blasting Creates a uniform matte finish that removes tool marks. Ideal for reducing reflectivity and improving surface uniformity.
Powder Coating Provides a hard, colourful coating that is tough and wear-resistant. Commonly used on enclosures, brackets, and consumer-facing components.
Chromate Conversion Plating Enhances corrosion resistance while retaining electrical conductivity. Often applied to aluminium components used in electronic assemblies. Commonly referred to as Surtec or Iridite.
Polishing Achieves a smooth, high-quality surface for aesthetic or functional use. Used in medical, optical, or high-spec applications where surface finish is critical.
Nickel Plating Applies a thin layer of nickel to improve corrosion and wear resistance. Provides a bright, uniform finish. Often used for decorative parts or where moderate hardness and conductivity are needed.
Zinc Plating Adds a protective zinc layer to prevent rusting, especially on steel parts. Usually applied with a clear, yellow, or black passivate. Cost-effective option for corrosion resistance in less aggressive environments.
Burnishing Improves surface finish and work-hardens the material through controlled deformation. Produces a smooth, polished surface without material removal. Enhances fatigue strength and aesthetic appearance.
Ultrasonic Cleaning Removes fine particles, oils, and machining residue using high-frequency sound waves. Commonly used as a pre-finishing or pre-assembly process. Ideal for complex geometries and internal features. Leaves no residue.
Assembly Combines multiple components into a finished or semi-finished assembly. Used to streamline production workflows. May include press fitting, fasteners, inserts, or other mechanical joining methods.
Tab four

Process Maximum Dimensions Notes
Milling Up to X: 1000 mm, Y: 600 mm, Z: 550 mm Based on Doosan and Matsuura 5-axis machines. Max Ø350 mm × 300 mm height for 5-axis work.
Turning Max billet Ø380 mm × 580 mm length
Max bar Ø65 mm × 1100 mm length		 Applies across Mazak, Doosan Puma, and CMZ lathes. Includes Y-axis and driven tooling.
Tab five

CNC equipment we use

Bridgeport VNM600

CNC Mill
X-Axis Travel: 600 mm
Y-Axis Travel: 400 mm
Z-Axis Travel: 350 mm

Doosan VC630 5AX

CNC Mill
X-Axis Travel: 650 mm
Y-Axis Travel: 750 mm
Z-Axis Travel: 500 mm

Bridgeport VMC1000 4AX

CNC Mill
X-Axis Travel: 1000 mm
Y-Axis Travel: 600 mm
Z-Axis Travel: 600 mm

Doosan DNM 4500

CNC Mill
X-Axis Travel: 800 mm
Y-Axis Travel: 450 mm
Z-Axis Travel: 510 mm

What components can we mill?

We can mill parts made from engineering plastics, aluminium, stainless steel, and other metals. Our CNC milling services cover a wide range of components and industries, giving you confidence in your part’s quality and performance. Here are some examples of component types we regularly mill.

Structural & mounting parts

We mill brackets, base plates, frames, and pressure vessels to tight tolerances. These parts play a vital role in mechanical strength and alignment, and are machined to deliver the rigidity and accuracy needed for performance-critical assemblies.

Housings & protective covers

Casings, housings, enclosures, and guards are machined to protect sensitive internal systems while maintaining access and functionality. Whether it's a robust outer shell or a compact internal shield, we ensure fit and finish match your technical needs.

Functional & moving components

From pivots, handles, and latches to arms, hooks, and scraper blades, we machine components that are built to move, connect, and engage. These parts are designed for durability, repeatability, and precision in motion-heavy environments.

Thermal, fluid, & precision components

We produce heatsinks, manifolds, and flow plates that manage heat and fluid movement, alongside high-precision parts like surgical instruments and implants. These components are milled to exacting standards for sectors where performance and compliance are non-negotiable.

Fixtures, tooling, & production support

We also manufacture jigs, guide pullers, connectors, and other tooling elements to support efficient assembly and testing processes. These production-critical components are milled for reliability, helping streamline your manufacturing workflows.

Examples of our high-quality CNC milled components

Interact in 3D

Electronic enclosure

Aluminium machining
Aluminium 6082 T6 with soft sulphuric blue anodising
Interact in 3D

Machined nylon prototype

Aluminium machining
Nylon
± 0.025mm
Interact in 3D

Machined OEM tooling piece

Aluminium machining
Black Nylon
±0.005"
Interact in 3D

Aluminium Machined Part

Aluminium machining
Material: Aluminium
Finish: Anodized
Weight: 150g

What our clients say

Leanne
Senior buyer at bicycle firm
We’ve worked with Penta on several complex projects, and their consistency and attention to detail have been second to none. The team is quick to respond and flexible.
Andrea
Buyer
Penta is highly recommended for their quality, responsiveness and customer service. We have experienced a lot of change with our parts and Penta has always accommodated the adjustments needed in a timely manner. The quality is 100%.
Mark
Senior buyer at coffee brand
The quality of the plastic mouldings you machined were exceptional.

Common questions

What is CNC machining used for in the aerospace industry?